1. Field of the Invention
Our invention relates to novel lighting devices which provide light for illumination as well as ambient light.
2. Description of Related Art
Electric lamps, and the light bulbs used therein, which provide illumination are well known and are widely used. These lamps and bulbs fall into two general categories, namely, incandescent and fluorescent. More recent developments in lighting have led to advancement in light emitting diodes (LEDs). An LED is a semiconductor device that emits visible light when an electrical current passes through it The light from an LED is basically monochromatic and the color of the light is determined by the particular material used in the semiconductor (although current applied to the LED can be used to vary the perceived color) LEDs have the advantage of low power requirements, high efficiency and long life. The outputs of several different color LEDs can be mixed so as to produce additional colors, including white light, and different brightness LEDs can also be used to provide background lighting to achieve desired ambient effects. However, they have limited brightness and therefore they are generally not suitable for illumination purposes. Instead, LEDs have been generally used for such applications as indicator lights, panel backlighting and fiber optic data transmission.
U.S. Pat. No. 6,149,283 discloses an LED lamp/bulb having a multicolor adjustor. This device comprises a base in which several LEDs capable of producing different colored light are mounted. Adjustable switches are provided for the different color LEDs so that the colors can be mixed in any desired ratio to produce desired lighting effects such as varying colors, including white light, and varying brightness. This patent acknowledges that the lumen output of LEDs is not as high as an incandescent source of the identical wattage.
U.S. Pat. No. 5,924,784 discloses providing ambient light (simulating a candle flame) from both a free-standing lamp and an Edison-style light bulb (i.e., a screw-in bulb that mates with a conventional light bulb socket) using LEDs. The flame simulation is provided through both color combinations emitted and flicker effects The patent states that it is directed to bulbs and lamps used for achieving soothing effects in memorials and the like.
U.S. Pat. Nos. 6,016,038, 6,150,774, 6,166,496, 6,211,626, 6,292,901 and 6,340,868 disclose various techniques and electrical circuits for controlling the light output of several LEDs according to predetermined programs.